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Hydrazine-coordinated cu chalcogenide complex and method of producing the same

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Hydrazine-coordinated cu chalcogenide complex and method of producing the same


A hydrazine-coordinated Cu chalcogenide complex obtainable by reacting Cu or Cu2Se and a chalcogen in dimethylsulfoxide in the presence of hydrazine and free of an amine solvent, and adding a poor solvent to the resulting solution or subjecting the resulting solution to concentration and filtration; and a method of producing a hydrazine-coordinated Cu chalcogenide complex, including reacting Cu or Cu2Se and a chalcogen in dimethylsulfoxide in the presence of hydrazine and free of an amine solvent, and adding a poor solvent to the resulting solution or subjecting the resulting solution to concentration and filtration.
Related Terms: Chalcogen Hydrazine

Browse recent Tokyo Ohka Kogyo Co., Ltd. patents - Kawasaki-shi, JP
Inventors: Masaru KUWAHARA, Koichi MISUMI, Hidenori MIYAMOTO
USPTO Applicaton #: #20120315210 - Class: 423413 (USPTO) - 12/13/12 - Class 423 
Chemistry Of Inorganic Compounds > Nitrogen Or Compound Thereof (except Ammonium Salt Of Non-nitrogen Acid) >Hydrogen Containing (e.g., Amide, Imide, Etc.)

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The Patent Description & Claims data below is from USPTO Patent Application 20120315210, Hydrazine-coordinated cu chalcogenide complex and method of producing the same.

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TECHNICAL FIELD

The present invention relates to a hydrazine-coordinated Cu chalcogenide complex and a method of producing the same.

BACKGROUND ART

In recent years, in consideration of environment, solar cells have been attracting a growing interest. In particular, attention has been drawn to chalcopyrite solar cells which are thin-film solar cells with high photoelectric conversion efficiency, and also CZTS solar cells which have a rare metal such as indium used in a chalcopyrite solar cell substituted with another element, and hence, research and development have been actively conducted.

A chalcopyrite solar cell is produced by forming a light absorbing layer prepared from a chalcopyrite material on a substrate. Representative elements of a chalcopyrite material include copper (Cu), indium (In), gallium (Ga), selenium (Se) and sulfur (S), and representative examples of a light absorbing layer include Cu(In, Ga)Se2 and Cu(In, Ga)(Se, S)2, which are abbreviated as CIGS and CIGSS, respectively. Recently, CZTS solar cell has been studied in which a rare metal indium has been substituted and is composed of, for example, copper (Cu), zinc (Zn), tin (Sn), selenium (Se) and sulfur (S). Representative examples of the light absorbing layer of such a solar cell include Cu2ZnSnSe4, Cu2ZnSnS4 and Cu2ZnSn(S, Se)4.

FIG. 1 is a schematic cross-sectional diagram of an example of a chalcopyrite solar cell or a CZTS solar cell.

As shown in FIG. 1, a chalcopyrite solar cell or a CZTS solar cell 1 has a basic structure in which a first electrode 3, a CIGS or CZTS layer 4, a buffer layer 5, an i-ZnO layer 6 and a second electrode 7 are laminated on a substrate 2 in this order. As the buffer layer, for example, a CdS layer, an ZnS layer and an InS layer are known.

Each of the first electrode 3 and the second electrode 7 has a terminal connected thereto, and each of the terminals is connected to a wiring. In such a chalcopyrite solar cell or a CZTS solar cell 1, an incident light entering in the direction of A is absorbed by the CIGS or CZTS layer 4 to generate an electromotive force, and an electric current flows in the direction of B.

The surface of the second electrode 7 is, for example, covered with an anti-reflection film layer 8 composed of an MgF2 layer for protection.

As a method of forming a CIGS or CZTS layer 4, a sputtering method and a coating method are known. However, in the sputtering method, the size of the apparatus tends to be scaled up, thereby deteriorating the yield. Therefore, diligent studies have been made on the coating method which enables production at a relatively low cost.

Generally, in a coating method of a CIGS layer, elements such as Cu, In, Ga, Se and S are dissolved in a specific solvent to prepare a coating solution, and the coating solution is applied to a substrate by a spin coating method or a dipping method, followed by baking, thereby forming a CIGS layer (see for example, Patent Document 1 and Patent Document 2).

In the preparation of a coating solution, there are known a method in which hydrazine is used as the solvent, and a method in which amine is added as a dissolution promoter instead of using hydrazine.

DOCUMENTS OF RELATED ART Patent Document

[Patent Document 1] U.S. Pat. No. 7,094,651 [Patent Document 2] WO2008/057119 [Patent Document 3] WO2008/063190 [Patent Document 4] U.S. Pat. No. 7,517,718

SUMMARY

OF THE INVENTION

However, in the preparation of a coating solution, when hydrazine is used as the solvent, a problem has conventionally been raised in terms of safety of the process due to chemical properties (explosiveness) of hydrazine.

In view of these problems, there have been demands for a coating solution which can assure safety of process. However, such a coating solution has not been proposed under these circumstances.

For solving the above-mentioned problems, the present invention employs the following embodiments.

The hydrazine-coordinated Cu chalcogenide complex is obtainable by reacting Cu or Cu2Se and a chalcogen in dimethylsulfoxide in the presence of hydrazine and free of an amine solvent, and adding a poor solvent to the resulting solution or subjecting the resulting solution to concentration and filtration.

Further, the method of producing a hydrazine-coordinated Cu chalcogenide complex according to the present invention includes reacting Cu or Cu2Se and a chalcogen in dimethylsulfoxide in the presence of hydrazine and free of an amine solvent, and adding a poor solvent to the resulting solution or subjecting the resulting solution to concentration and filtration.

In the present invention, a hydrazine-coordinated Cu chalcogenide complex and a DMSO solution are provided which are usable for forming a light-absorbing layer of a chalcopyrite solar cell or a CZTS solar cell. Therefore, when coating is performed in the formation of a light-absorbing layer of a chalcopyrite solar cell or a CZTS solar cell, there is no need to use dangerous hydrazine in the application of the coating solution. As a result, safety of the process in the formation of a light-absorbing layer can be assured.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional diagram of an example of a chalcopyrite solar cell or a CZTS solar cell.

FIG. 2 is the results of thermogravimetric analysis of the hydrazine-coordinated Cu chalcogenide complex produced in Example 1.

FIG. 3 is the results of X-ray diffraction analysis of the residue obtained from the thermogravimetric analysis of the hydrazine-coordinated Cu chalcogenide complex produced in Example 1.

FIG. 4 is the results of X-ray diffraction analysis following formation of a film in Example 1.

FIG. 5 is the results of X-ray diffraction analysis following formation of a film in Example 2.

FIG. 6 is a cross-sectional diagram of the CZTS layer formed in Example 2 as measured by a scanning electron microscope.

DETAILED DESCRIPTION

OF THE INVENTION Hydrazine-Coordinated Cu Chalcogenide Complex

Hereinbelow, the hydrazine-coordinated Cu chalcogenide complex of the present invention will be described.

The hydrazine-coordinated Cu chalcogenide complex is obtainable by reacting Cu or Cu2Se and a chalcogen in dimethylsulfoxide in the presence of hydrazine and free of an amine solvent, and adding a poor solvent to the resulting solution or subjecting the resulting solution to concentration and filtration.

More specifically, for example, a Cu metal and a chalcogen are reacted in DMSO in the presence of hydrazine, and stirred at room temperature for about 3 to 7 days. Then, hydrazine is removed from the resulting solution while flowing nitrogen, followed by filtration. Thereafter, a poor solvent is added to the filtrate to perform a recrystallization, thereby obtaining a black hydrazine-coordinated Cu chalcogenide complex.

Alternatively, the hydrazine-coordinated Cu chalcogenide complex of the present invention can be produced as follows. A metal Cu and 2 to 4 equivalents of Se are stirred in DMSO at room temperature for 3 days to 1 week in the presence of 2 equivalents of hydrazine relative to the Cu metal. Then, the remaining hydrazine is removed under reduced pressure, followed by concentration. The resulting concentrated solution is subjected to filtration, thereby obtaining a hydrazine-coordinated Cu—Se complex/DMSO solution.

As the chalcogen, Se or S can be used, and Se is preferable. As Cu, not only a Cu metal, but also copper selenide (Cu2Se) may be used. As the poor solvent, an alcohol solvent is preferable, and isopropanol (IPA) is more preferable.

As hydrazine, anhydrous hydrazine may be used, although hydrazine monohydrate or hydrazine having water added thereto (hereafter, referred to as “water-containing hydrazine”) is preferable. Anhydrous hydrazine vigorously reacts with selenium, whereas hydrazine monohydrate or a water-containing hydrazine mildly reacts with selenium. Therefore, hydrazine monohydrate or a water-containing hydrazine is preferable in terms of ease in handling in the synthesis process. The water content of the water-containing hydrazine is preferably 63% by weight or more.

With respect to the amount of Cu and the chalcogen, it is preferable to use 2 to 4 mol of the chalcogen, per 1 mol of Cu. Further, it is preferable to dissolve Cu and the chalcogen in DMSO having about 2 mol of hydrazine added thereto.

The generation of the hydrazine-coordinated Cu chalcogenide complex described above can be expressed by a chemical formula (1) shown below.

As described above, the hydrazine-coordinated Cu chalcogenide complex of the present invention is obtained by dissolving the raw materials in DMSO, followed by recrystallization. As a result, the thus obtained hydrazine-coordinated Cu chalcogenide complex is extremely soluble in a DMSO solution.

Further, with respect to the hydrazine-coordinated Cu chalcogenide complex of the present invention, since the coating solvent does not contain hydrazine, the chemical properties (explosiveness) of hydrazine in the formation of a light-absorbing layer would not be of any problems, thereby improving the safety of the production process.



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stats Patent Info
Application #
US 20120315210 A1
Publish Date
12/13/2012
Document #
13157885
File Date
06/10/2011
USPTO Class
423413
Other USPTO Classes
International Class
01B21/16
Drawings
6


Chalcogen
Hydrazine


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